Chapter 17 Classification of Organisms

1
Chapter 17Classification of Organisms
2
Section 1 - Biodiversity

• Biologists have named and classified almost 2
  million species. They believe the total is much
  greater.
• Various methods of classification have been used
  to organize their knowledge of the tremendous
  number of species. Species have been placed in
  categories based on particular characteristics.

3
Section 1 - Biodiversity

• Classifying Organisms
• Naturalists have invented several systems for
  categorizing biodiversity, which is the variety
  of organisms considered at all levels from
  populations to ecosystems.

4
Section 1 - Biodiversity

• Taxonomy
• Naturalists replaced Aristotles classification
  system because it did not adequately cover all
  organisms and because his use of common names was
  problematic.
• Taxonomy is the science of describing, naming,
  and classifying organisms.

5
Section 1 - Biodiversity

• Taxonomy (cont.)
• The Linnaean System
• Carolus Linnaeus devised a seven-level
  hierarchical system for classifying organisms
  according to their form and structure.
• From the most general to the most specific,the
  levels are kingdom, phylum, class, order,
  family,genus, and species.

6
Section 1 - Biodiversity

• Classification Hierarchy of
• Organisms

7
Section 1 - Biodiversity

• Linnaeus's Levels of Classification

8
Section 1 - Biodiversity

• Levels of Classification
• Binomial Nomenclature
• An important part of Linnaeuss system was
  assigning each species a two-part scientific
  namea genus name, such as Homo, and a species
  identifier, such as sapiens.
• This system of a two-part name is known as
  binomial nomenclature.

9
Section 2 - Systematics

• Systematics is the goal to classify organisms in
  terms of their natural relationships.

10
Section 2 - Systematics

• Phylogenetics
• A modern approach to taxonomy is systematics,
  which analyzes the diversity of organisms in the
  context of their natural relationships.
• When classifying organisms, scientists consider
  fossils, homologous features, embryos,
  chromosomes, and the sequences of proteins and
  DNA.

11
Section 2 - Systematics

• Phylogenetics (cont.)
• A phylogenetic diagram displays how closely
  related a subset of taxa are thought to be.

12
Section 2 - Systematics

• Phylogeny

13
Section 2 - Systematics

• Phylogenetics (cont.)
• Evidence of Shared Ancestry
• Homologous features as well as similarities in
  patterns of embryological development provide
  information about common ancestry.

14
Section 2 - Systematics

• Cladistics
• Cladistics uses shared, derived characters as the
  only criterion for grouping taxa.

15
Section 2 - Systematics

• Cladogram Major Groups of Plants

16
Section 2 - Systematics

• Cladistics (cont.)
• Molecular Cladistics
• Molecular similarities (such as similar amino
  acid or nucleotide sequences), as well as
  chromosome comparisons, can help determine common
  ancestry.
• Chromosomes
• Analyzing karyotypes can provide more information
  on evolutionary relationships.

17
Section 2 - Systematics

• Similarities in Amino Acid Sequences

18
Section 2 - Systematics

• Cladistics

19
Section 2 - Systematics

• Phylogenetic Diagram of Mammals

20
Section 3 Modern Classification

• Biologists continue to develop taxonomies to
  organize lifes enormous diversity. Revisions are
  made to reflect current hypotheses of the
  evolutionary relationships between groups

21
Section 3 Modern Classification

• The Tree of Life
• Revising the Tree
• The phylogenetic analysis of rRNA nucleotide
  sequences by Carol Woese led to a new tree of
  life consisting of three domains aligned with
  six kingdoms.

22
Section 3 Modern Classification

• Three Domains of Life
• The three domains are Bacteria, Archaea, and
  Eukarya.
• Domain Bacteria
• Domain Bacteria aligns with Kingdom Eubacteria,
  which consists of single-celled prokaryotes that
  are true bacteria.

23
Section 3 Modern Classification

• Three Domains of Life (cont.)
• Domain Archaea
• Domain Archaea aligns with Kingdom
  Archaebacteria, which consists of single-celled
  prokaryotes that have distinctive cell membranes
  and cell walls.
• Domain Eukarya
• Domain Eukarya includes the kingdoms Protista,
  Fungi, Plantae, and Animalia.
• All members of this domain have eukaryotic cells.

24
Section 3 Modern Classification

• Phylogenetic Diagram of Major Groups of Organisms

25
Section 3 Modern Classification

• Six Kingdoms

26
Section 3 Modern Classification

• Kingdom and Domain Characteristics